Acquired reading disorders constitute a frequent and often disabling concomitant of the language disorders often associated with stroke, head trauma, dementia and brain tumors. In recognition of this fact, and increasing amount of attention has been devoted to the dyslexias in recent years, with the expectation that a better understanding of the normal processes by which reading is accomplished will lead to the development of more efficacious methods for the rehabilitation of patients with acquired dyslexias as well as the training of individuals with developmental reading disturbances and normal readers. The work outlined in this proposal is intended to contribute to our understanding of reading processes, initially by addressing three major unresolved issues in this field. Experiment I is designed to contrast and compare two recently proposed models of the reading process. The modified dual-process model of Sahllice, Warrington and McCarthy (1983) and the three process model of Schwartz, Saffran and Marin (1980), which incorporates a word-specific print-to-sound mapping mechanism, will be contrasted in studies conducted with semantic dyslexics. Experiment II is designed to determine if the often reported correlation between an impairment in the ability to read grammatical words (functors) and an impairment in the ability to read via phonologic conversion reflects the fact that, as some investigators have suggested, functors are obligatorily read by the phonologic process; an alternative explanation for this apparent association, suggested by the author's previous work, is that these functions have overlapping anatomic substrates and therefore are often injured by the same pathologic process. The question will be addressed in a series of three investigations involving phonologic dyslexics and normal readers. Experiment III is designed to assess the reading capability of the right hemisphere. Using patients in whom visual verbal input is restricted to the right hemisphere by virtue of an infarct involving the splenium of the corpus callosum as well as the left occipital pole, reading aloud and for comprehension will be assessed using a variety of neuropsychological tests. The right hemisphere reading hypothesis predicts that this patient group will show some evidence of preserved reading and that reading comprehension will surpass the ability to read aloud.